Cap and method of making the same



, L. SCHREYER 2,318,185

CAP AND METHOD OF MAKING THE SAME Filed Nov. 16, 1939 BY h/w w ATTORNEYSPatented May 4, 1943 car AND METHOD or MAKING THE smut:

. Leo Schreyer, Bratenahl, Ohio, assignor to Intel-national ElastitCorporation, a corporation of Ohio Application November 16, 1939, SerialNo. 304,874

11 Claims.

This invention relates to plastic film and particularly to elasticfilm-like gelatin caps which are used to hermetically seal the closuresof bottles and similar containers.

As conducive to a clearer understanding of this invention, it may bewell to point out that hermetic seals of this type in the past'haveconsisted of thin film-like capsules or membranous coat ings. The formerhave been usually roughly preshapedand applied to the bottle closure andneck while in a plastic state so that when hydrated, the capsules wouldfit snugly over and aroundthe closures. The latter coatings have beenapplied simply by dipping the sealed mouth of the inverted container ina viscous liquid which, when dried in the air, hardened and formed acovering for the primary closure and bottle neck.

Th film-like capsules have been made generally of cellulose acetate orother cellulose derivatives and while they are vapor and water proof,they are not elastic, they are easily afiedted by climatic conditionsand their colors are not clear but instead have a faded appearance.Their inelasticity makes them difflcult and expensive to apply to thebottle neck. Their inability to withstand climatic conditions makes themextremely hard and brittle under some conditions and soft and stickyunder others. Their lack of luster and lifeless appearance makes theminattractive for commercial purposes. In addition, these capsules arehighly inflammable and necessarily must be stored and shipped in liquidfilled containers.

Gelatin capsules of this type were expensive to produce. Theirappearance left much to be desired for commercial purposes. elasticityand became very fragile in the warmer and colder climates. While theywere for most purposes better than cellulose derivative covers. theirmanufacture in large quantities did not lend itself to automaticproduction. Much hand labor had to be used to remove the cap forms fromthe pegs or mandrels on which they were dried and took shape.

The membranous coating applied to the closures in a liquid statenecessitated the tipping of the bottle upside down. The tipping hascertain obvious disadvantages. Also, such covers were not lasting andsoon became too soft and sticky for convenient handling. However, theirapplication did not cause air bubbles which frequently were hard toeliminate from the capsule type of seals.

It is therefore the primary object of this invention to provide amaterial which is relatively They also lacked a easy and-inexpensive tomanufacture and use 'for the purposes mentioned. I

Another object is to provide bottle closure caps which are resilientbefore being applied and substantially inelastic thereafter; which arealso non-inflammable, non-odorous, tasteless and'attractive inappearance.

A further object is to'provide a substance and an article of the typementioned which is durable, moisture resisting, ether and gasproof andcapable of withstanding extreme climatic conditions for long periods oftime.

Still another object is to provide a gelatin capsule for sealing abottle which capsule may be stored and shipped in' a dry and partiallypreformed state and which capsule is made ready for final application bythe mere soaking of it in cold water for a relative short period oftime, but which capsule becomes impervious to water after it is finallyset.

A still further object is to provide a membranous capsule which may bemade transparent or opaque, which may be colored or polished as desiredand which may be printed on.

These and other objects as well as a further understanding of theinvention maybe had by referring to the following description andclaims.

Fig. 1 diagrammatically illustrates how a form or mandrel I is dippedinto a liquid 2. This liquid may be the coating bath, whose majoringredient is gelatin, or it may be the fixing bath.

Fig. 2 is a cross-section, partially in elevation, showing the completedcap 3.

Preparatory to making a composition gelatinous material and applying theprocess of this invention, there is provided a rack or base on which aplurality of pegs or mandrels are mounted in rows. These mandrels serveas molds for the capsules and are slightly smaller in diameter than thenecks of the bottles which are intended to be sealed with them. As thesemandrels per se form no part of the instant invention and furthermore astheir use and construction is well known to the art, a precisedescription of them is believed not necessary and hence will bedispensed with.

The process itself consists of three essential steps or operations.There is first, the preparation of the initial or base composition andthe molding thereof; next, the preparation of the main body compositionand its application to the base composition: and finally, thepreparation of a fixing bathand treatment therein of the two combinedaforementioned compositions. Each of these steps will now be describedseparately and in the order in which they take .place.

The base composition has for its main purpose the prevention of thegelatinous compound adhering to the mandrels after the compound is fixedand dried. In its preparation:

.5 kilogram of gelatin and 1.5 kilograms of regular bone glue areallowed to soak in a quantity of soft cold water until both the gelatinand the glue have absorbed as much water as possible and until bothsubstances have stopped swelling; the bone glue is an impure form ofgelatin so that the major ingredient of the inner layer or basecomposition is gelatin;

8 grams of soluble starch are dissolved in warm water and stirredconstantly until the solution is semi-transparent or has an opalescentappearance;

50 grams of gum arabic are thoroughly dissolved in about .5 liter of hotwater;

To 100 c. c. of 96% alcohol, which has previously been denatured by asmall quantity of 90% carbolic acid, add 7 grams of phenol or somehydroxyl derivative which is a good preservative for the gelatinouscomposition;

10 grams of boric acid crystals are dissolved in approximately 150 c. c.of hot water;

160 c. c. of 50% neutral Turkey red oil is prepared, or in its stead 160c. c. of sulfonated castor oil is used;

170 c. c. of glycerin having a Baum hydrometer test or density of 30 islikewise prepared;

c. c. of some anti-bactericide, mould preventative or sterilizingsolution is thoroughly mixed with 15 c. c. of water;

And a last solution is made by slowly mixing 15 liters of oxgall with 75c. c. of a 90% solution of carbolic acid.

The pieces of softened gelatin and glue are placed in a large doubleboiler, the temperature of which is maintained at 40 C. by automaticmeans and thermostatic control. The opalescent starch solution is addedthereto. The gum arabic solution is next added and the mixture isthoroughly homogenized.

When the aforementioned compounds are mixed thoroughly, the alcohol,boric acid, Turkey red oil. glycerin and sterilizing solutions are eachadded to the viscous mass in the double boiler in the order just stated.After these solutions are thoroughly mixed with the mass, smallquantities of the oxgali solution are slowly mixed therewith until theentire quantity of approximately 16 liters is thoroughly infused andmixed.

The aforementioned compound is then transferred to a vacuum-pan orvacuum-boiler in which it gradually cools and remains for abouttwenty-five minutes. Quantities of this cooled mixture are then pouredinto long troughs and the cap forms or mandrels are dipped therein. Whenremoved, the mandrels have a coating of the materials, which when driedis very thin and The main body composition or second coat consists of 15kilograms of pork strip gelatin which is allowed to soak in softenedcold water. The gelatin should be of the: type and quality that has ahigh melting point and after it has swollen to its maximum size and hasabsorbed as much water as possible, it is placed in a large doubleboiler, the temperature of which is automatically maintained between 54and 57 C.

One and fifteen-hundredths kilograms (1.15 kilograms) of salt are boiledin a quantity of water and when dissolved are thoroughly mixed with thegelatin. It is important that salt be used which does not have iodine orsimilar chemicals in it.

A solution of one liter of water, 2.5 liters of denatured alcohol and 28grams of a good phenol sterilizer is made and mixed with the saltedgelatin. The mixture is slowly but thoroughly stirred and agitated untilall the lumps disappear and the mass has a smooth even consistency.

Eight hundred c. c. (800 c. c.) of glycerin are directly added to themixture and thoroughly mixed with it.

Twenty grams (20 grams) of boric acid are dissolved in hot water andadded to the mass.

Twenty grams (20 grams) of pure light Vaseline are next added thereto.

Twenty-five c. c. (25 c. c.) of a liquid sterilizer are mixed with alike amount of water and then added to the gelatinous mixture.

One hundred and fifteen c. c. (115 c. c.) of Turkey red oil orsulfonated castor oil is mixed therein.

After the entire gelatinous viscous mass is homogenized thoroughly, anysuitable coloring matter may be added to the compound.

At this point the material is tested with a viscosimeter and if itgauges a consistency of 28 or 29, it is in proper condition. If ithappens to be too thick, water is added to soften it, or if on the otherhand it is too fluid, it should be cooked a while longer.

If the material gauges properly, it is immediately poured into a closedpressure boiler which is being heated at a constant, automaticallyregulated temperature oi between 54 and 58 C. It is kept in vacuum andso heated until the composition "breaks." That is, at a certain time.approximately thirty minutes after being put into the vacuum boiler, anend-point is reached and further reaction of the aforementionedchemicals ceases. At this point the alcohol vapors which are drawn outof the material by the vacuum, are drawn oil through suitable conduitsand allowed to escape. It should be particularly noted that atemperature of 69 C. is not reached in the vacuum boiler as at thattemperature, the mass peptonizes and undergoes certain fundamentalchanges which make the material unsuited for the purposes intended.

When this second quantity or main mass of material has been properlyprepared, mixed and treated, it is poured into long troughs and themandrels heretofore referred to, and which mandrels are still coveredwith the dried initial or base composition, are dipped into it. Afterthe second immersion, the main coat is allowed to dry. The second coat,however, is many times thicker and heavier than the base coat.

The third and last step in the process, sometimes referred to herein asthe fixing, hardening or glazing operation is the most, important andits materials and steps must be measured and timed with great accuracy.

A first solution is made of 3500 grams of Pure chrome alum and liters ofwater.

A second solution is made of 2500 grams of potassium dichromate crystalsdissolved in 100 liters of water.

A third solution is similarly made of 3000 grams of pure potassium alum.

A fourth container contains a quantity of a 40% solution offormaldehyde.

Next, 10 liters of the first solution, 5 liters of the second solution,1.2 liters of the third solution and 2.9 liters of the formaldehydesolution are thoroughly mixed with 400 liters of water. Hence thehardening or condensing bath contains 350 gms. of chrome alum, 125 gms.of potassium dichromate, 36 gms. of potassium alum,and about 1044 gms.of formaldehyde. The standard solution of formaldehyde contains 40% offormaldehyde by volume, and about 37% of formaldehyde by weight. Itcontains from 36-38 gms. of formaldehyde in 100 cc. Therefore 2.9 litersof said solution contains from 1044 gms. to 1082 gms. of dissolvedformaldehyde. In this final mixture the caps, while still on themandrels, are dipped for two and one-quarter (2%) minutes.

The mandrels are then taken out, inverted and the caps permitted to dryin normal daylight or in the presence of ultra-violet rays. Afterdrying, the caps fall off the mandrels of their own accord. and aresorted, stacked and packed for delivery or for subsequent application onbottle closures.

As the fixing bath weakens, small quantities of the four solutions areadded so that its Strength is regenerated and maintained and so thatproper chemicalreaction may be had on the caps during their two andone-quarter (2%) minute immersion.

Before the caps are applied to the bottles, they are soaked in coldwater for about one hour after which time they become soft, pliable andelastic. When dried on the bottles, they contract evenly and make anair-tight seal. Thereafter they are impervious to moisture and are notaffected by temperature or atmospheric conditions.

The caps may be printed on either after or before the fixing or thirdstep. However, if the caps are printed on before the fixing operation,the ink used must not contain oil or any greasy substance as suchsubstances have a deleterious efiect on the fixing solution.

By way of further explanation; the oxgall, which is an organic, fattyblood product, has certain properties which prevent the compound frommelting below a temperature of 50 C., also it, because of its unctuousnature, facilitates removal (dropping ofi) of the finally formedcapsules from the mandrels. The starch and gum arabic both of which havethe qualities of very easily absorbing water, cause an internal pressurethat facilitates and in part causes the removal or dropping ofi of thefinally formed capsules from the mandrels. The gum arabic and the starchalso contribute certain qualities of expansion and flexibility. TheTurkey red oil aids or hastens the mixing of the oils with the water andtends to prevent the formation of air bubbles in the compound. The boricacid, as an antiseptic, assists or supplements the other sterilizingagents in preventing the formation of moulds and helps preserve thefinal composition.

Salt increases the density and specific gravity of the compound andthereby gives the final product a more brilliant and attractiveappearance. The alcohol lowers the boiling point of the liquids and alsoincreases its smoothness. The glycerin assists in the generalhomogenization of the materials.

Of the fixing bath, the first solution, containing chrome alum as atannin, hardens and sets the material and regulates hygroscopic actionof the gelatin. The second solution, containing potassium dichromate,causes the capsules to be affected by actinic rays and to becomepolymerized thereby. The third solution, containing potassium alum,affects only the outer exposed surface of the capsule so that it takeson a hard, smooth and glossy surface. As gelatinous substances have atendency to lose or absorb color, the formaldehyde reacts in a mannerwhich revives and enhances the natural color of the article, and

in addition hereto, is a hardening agent.

It has been found from experience and repeated tests that a gelatinousfilm-like material made in accordance with this invention has an innersurface which is approximately one-half as hard as the outer surface.This is because the four aforementioned solutions each affect the outermaterial during the two and one-quarter (2%) minute'immersion in adifferent manner and to a diflerent degree. The hardness or texture ofthe final cap varies gradually between its inner and outer surfaces,with the result that the article has all the advantages ofa soft pliablecap combined with those of a hard inelastic cap.

The major ingredient'of the improved bottle cap is gelatin. The innerlayer and the outer layer are of different compositions. The outer layeris more viscous than the inner layer.

One of the many advantages of this product over other similar articlesis that the gelatinous seal may be made very thin but durable, therebysaving material. Also such seals will not be affected by chemicals suchas, ether or alcohol. This feature being particularly valuable in thebottling of medicines, perfumes, fermented or distilled liquors and manysuch products. Another advantage is that the caps may be applied rapidlyby persons with relatively little training or experience and also nospecial or expensive machines are required to affix them.

It will now be clear that there is provided by this invention a methodand composition for making plastic film and articles therefrom whichaccomplishes the objects of the invention. While the invention has beendescribed in a specific form and while certain broad general terms havebeen used, it is to be understood that the embodiment of the inventionas described is suggestive only and is not to be considered in alimiting sense as no limitations upon the invention are intended otherthan those imposed thereon by the scope of the appended claims.

I claim:

1-. A method of making a cap which consists in forming the cap blankwith an inner layer and an outer layer which is integral with said innerlayer, said layers being of respectively difi'erent compositions, themajor ingredient of each layer being gelatin, and treating said blankonly at its layer being more viscous and containing a greater proportionof gelatin than the inner layer, and treating said composite blank onlyat the outer surface of its outer layer with a fixing bath which hardensthe outer layer more than the inner layer. f

3. A method according to claim 2 in which the hardening liquid containschrome alum, potassium dichromate, potassium alum and formaldehyde.

4. A method or making a cap whose major ingredient is gelatin, whichconsists in forming a cap blank with an inner layer and with an outerlayer which is integral with the inner layer and whichis thicker thanthe outer layer, the major ingredient of each said layer being gelatin,said outer layer having a greater percentage of gelatin than the innerlayer, treating said blank with a hardening liquid which has a greaterhardening eflectupon the outer layer than on. the inner layer.

5. A method according to claim 4 in which the inner layer issubstantially free from salt (NaCl) and in which the outer layer hassalt in the percentage of more than 7% of the gelatin.

6. A cap comprising an inner layer and an integral outer layer which isthicker than said inner layer, the major ingredient of each layer beinggelatin, said inner layer containing suflicient ox-gall to render thecap substantially nonadherent to a dipping form on which said cap isformed.

7. A cap comprising an inner layer and an outer layer which is thickerthan the inner layer and which is integral with the inner layer, themajor ingredient of each layer being gelatin, the

proportion of gelatin-in the outer layer being greater than in the innerlayer, a major propor tion of the gelatin in the inner layer being boneglue, each layer containing ingredients additional to the gelatin, theinner layer including ox-gall, the outer layer containing petrolatum,each layer containing a suflicient proportion of a substantially neutralsulfonated oil to provide a uniform mixture ofthe gelatin and of theother ingredients of the respective layer.

' of gelatin, the inner layer including starch and gum arabic, therespective proportions of gelatin and of starch and of gum arabic insaid inner layer being substantially 2000 to 8 to 50.

10. A bottle cap whose major ingredient is water-insoluble and hardenedgelatin, said cap being resilient in the dry condition and becoming softand pliable when soaked in cold water. the outer surface portion of thecap having a larger percentage of gelatin and being harder than theinner surface portion of the cap.

11. A bottle cap whose major ingredient is water-insoluble and hardenedgelatin, said cap being resilient in the dry condition and becoming softand pliable when soaked in cold water, the outer surface portion of thecap having a larger percentage of gelatin and being harder than theinner surface portion of the cap, said outer surface portion containingsalt in the proportion of substantially seven per cent of the gelatin insaid outer surface portion.

LEO SCHREYER.

